abstract
Two nickel(II)-complexes, [Ni-II(H3L)(2)] (ClO4)(2) ( [1]-(ClO4)(2)) and [Ni-II(HL)(2)] (2), containing the redox-active tridentate ligand N-1-(2-aminophenyl)benzene-1,2-diamine (H3L) have been synthesized. Complex [1] (ClO4)(2) is octahedral containing two neutral H3L ligands in a facial coordination mode, whereas complex 2 is a singlet diradical species with approximately planar configuration at the tetracoordinate metal atom with two pendant NH2 side arms from each of the coordinated ligands. Both complexes are found to be chemically interconvertible; complex [1](2+) gets converted to complex 2 when exposed to base and oxygen via simultaneous deprotonation and oxidation of the coordinated ligands. Molecular and electronic structures of the isolated complexes are scrutinized thoroughly by various spectroscopic techniques, single crystal X-ray crystallography, and density functional theory. The observed dissociation of a ligand arm upon oxidation of the ligand was exploited to bring about catalytic alcohol oxidation using coordinatively saturated complex [1] (ClO4)(2) as a catalyst precursor. Both the complexes [1] (ClO4)(2) and 2 were tested for catalytic oxidation of both primary and secondary alcohols.
keywords
TRANSITION-METAL-COMPLEXES; ACTIVE TRIS(AMIDO) LIGAND; KUMADA COUPLING REACTIONS; PLANAR NICKEL-COMPLEXES; CORRELATED AB-INITIO; PI-RADICAL LIGANDS; ELECTRONIC-STRUCTURE; PALLADIUM(II) COMPLEX; REACTIVITY; DENSITY
subject category
Chemistry
authors
Sikari, R; Sinha, S; Jash, U; Das, S; Brandao, P; de Bruin, B; Paul, ND
our authors
Paula Cristina Ferreira da Silva Brandão
Assistant Researcheracknowledgements
The research was supported by CSIR, New Delhi (Project: 01(5234)/15//EMR-II) and DST (Project:YSS/2015/001552). RS. thanks RGNF and S.S. thanks IIESTS for fellowship support. Financial Assistance from IIESTS is acknowledged. P.B. thanks CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement